Left before old weakling gets to do something with little effect (3-6)

'little effect' is the definition.
I know nothing about this answer so I can't tell whether this works.

'left before old weakling gets to do something' is the wordplay.
'left before' becomes 'l' (common abbreviation. I am not sure about the 'before' bit.).
'old' becomes 'o' (abbreviation).
'weakling' becomes 'wimp' (wimp is a kind of weakling).
'gets' is a charade indicator (letters next to each other).
'to do something' becomes 'act' (to act is to do something).
'l'+'o'+'wimp'+'act'='LOW-IMPACT'

'with' acts as a link.

Can you help me to learn more?